Evaluate sin(-3pi)

$\sin (- 3 π)$

Add full rotations of $2 π$ until the angle is greater than or equal to $0$ and less than $2 π$ .

$\sin (π)$

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.

$\sin (0)$

The exact value of $\sin (0)$ is $0$ .

$0$